As is known, cargo drops by parachute from aircraft have been used extensively in military operations and disaster relief situations. In one type of parachute cargo delivery system, cargo bundles, which may be on pallets, are guided for movement along the longitudinal axis of the aircraft between parallel guide rails secured to the aircraft floor. Upon a nose-up attitude of the aircraft, the cargo pallets move aft and out of a cargo receiving and delivery opening and then descend to the ground under the restraint of a parachute.
In certain types of aerial delivery systems of this sort, the cargo bundles are restrained by fore and aft restraint straps during normal flight conditions. The aft restraint straps, however, must be severed during an airdrop operation to permit the bundles to move backwardly through the rear cargo receiving and delivery opening by gravitational pull when the aircraft adopts a nose-up attitude.
In the past, the aft straps have been severed during an airdrop operation by means of a retrieval winch line and guillotine knife which severs the aft strap or straps holding the cargo bundles on the aircraft. The winch cable is usually strung the length of the cargo compartment in a more or less makeshift fashion to reach the restraint straps at the aft end of the cargo floor. Slackness in the strap due to bundle shifting and/or a dull knife can cause the system to become unreliable at times, resulting in delays during the airdrop operation which cause the bundles to overshoot the drop zone.